Headlight ifor automobiles



Apr. 10, 1923;

1,451,161 E. B. HELM HEADLIGHT FOR AUTOMOBILES Filed Dec. 1, 1920OwMWJ/M my.

Patented Apr. 10, 1923.

UNITED STATES PATENT QFFICE.

EMERSON IB. HELM, OF CLEVELAND, OHIO, ASSIGNOR 0F ONE-THIRD T0 CHARLESL. GEBAUER AND ONE-THIRD T0 JAMES BENNER, BOTH 0F CLEVELAND, OHIO.

HEADLIGHT FOR AUTOMOBILES.

Application filed December 1, 1920. Serial No. 427,519.

To all whom it may concern:

Be it known that I, EMERSON B. HnLM, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented a certain new and useful Improvement in Headlights forAutomobiles, of which the following is a full,clear, and exactdescription, reference being had to the accompanying drawings.

This invention relates to automobile headlights and has for its objectthe provision of a device of this character of very great simplicitywhich shall utilize all the rays from the light source beneficially andwithout the production of glaring'or dazzling rays projected at such an.angle as to be contrary to law or obnoxious to travelerspassing in theopposite direction. Other objects of the invention are the provision ofa new and improved lamp bulb for automobile headlights which can be usedwith a plain paraboloid reflector and plain glass closure without wasteof light or producing a glare; the provision of a headlight which shallconform to all requirements of law and courtesy merely by the use of aSpecial bulb and this without any material increase in the cost of suchbulb; while further objects and advantages of the invention will becomeapparent as the description proceeds.

It is the well known property of a paraboloid reflector that all raysarising exactly at its focal point are reflected forward in a strictlyparallel beam. However, no known light source is restricted to ageometrical point, and the portions thereof which fall outside of thislimit diverge from parallelism, some to a beneficial ex tent and othersto an obnoxious extent. It-

is also known in respect of paraboloid reflectors that all rays whicharise forward of the focal point are reflected forwardly converging andall rays arising to the rear of the focal point are reflected downwardlydiverging; and use has been suggested to be made of this property bydisplacing the upper half of the reflector forwardly of the lower halfso that a single light source located between thefocal points of therespective sections would have its rays cast downwardly by each, in oneas a result of convergence and in the other case as a result ofdivergence. This necessitates the employment of a special reflectorwhich is expensive to make and has certain practical drawbacks.According to my invention the same identical result is achieved with aplain paraboloid reflector by the use of a light source made in twoparts longitudinally spaced along the paraboloid axis and located uponopposite sides of the focal point, the source which is forward of thefocal point illuminating only the upper half of the reflector wherebyits rays are cast downwardly converging, and the source which lies atthe rear of the focal point illuminating only the lower half of thereflector so that all the rays are cast downwardly diverging and toproduce such a source I employ a peculiar kind of light bulb which Iwill now describe.

In the drawings accompanying and forming a part of this application Ihave illustrated certain simple embodiments of my invention. Fig. 1represents the forward end of an automobile equipped with a headlight ofmy invention; Fig. 2 is a diagrammatic view of a paraboloid reflector incombination with a source of the type specified; while Figs. 3, t and 5are sectional views of light bulbs embodying my improvements inpractical form.

Describing the parts by reference characters, A represents a plainparaboloid reflector whose axis is indicated at aa and focal point at f.m and a represent the two parts of the source, the portion m beingforward of the focal point and giving rise to the rays o(); and the partat being at the rear of the :focal point and giving rise to the raysp-p.

Each source is preferably shielded from the opposite half of thereflector by means of a concave shield R which is preferably made ofasmooth and refractory material so as to enable the utilization of therays which fall thereon; and the sides of these shields are preferablybrought sufliciently beyond the axial line on each side as shown at 1-rto enclose the sides of the source, thus preventing lateral raystherefrom from falling on the side portions of the reflector and givingrise to the glare which is most objectionable.

In Fig. 3 these considerations are shown embodied in the most simpleform. 1 represents the spherical bulb and 2 the glass post sealedtherein and carrying the leading-in wires 3 and 4, the former beingattached to the metal shell 5 and the latter to the central insulatedcontact 6. Carried by this post is the supporting rod 7 to whose outerend is attached thereflector 8 which comprises two hemispherical cupsplaced side by side along the axis of the lamp and facing in oppositedirections. Inside these cups are placed the filaments 9 and. 10respectively, one end of the filament 9 being connected to theleading-in wire 3 and one end of the filament 10 to the leading-in wire4 the opposite ends of the filaments being grounded to the reflector 8which is itself electrically insulated. I have shown the filamentarywires as running generally in an axial direction, since lateraldivergence from the axis produces deviations of rays which areparticularly hard to correct. The lips of the cups project a sufiicientdistance in their respective directions toshut off all lateral rays asshown at 12-12, and the insides of the cups are preferably polished soas to form miniature reflectors. The member 8 is preferably made ofhighly refractory metal like tungsten or molybdenum inasmuch as itsproximityto the incandescent filament causes it to become highly heated.

In the modification shown in Fig. 4 the reflector element 8, instead ofcomprising two hemispherical cups placed side by side along the axis,consists of two comparatively flat dishes. arranged baclr to back, whilethe filaments 9 and 10 are arranged one in each as before, and arecarried by the leading-in wires 3, 4:, but instead of being grounded tothe reflector they are here shown as con nected together in series by ashort conduc tor 13. The use of this wire 13 enables the reflector to bemade of non-conducting material if desired such as porcelain, glass, orbetter still, some of the refractory earths;

and this indeed can be used for the reflector 8 shown in Fig. 3, asuitable hole being left for the filament to pass through.

In the embodiment shown in Fig. 5 the reflector 8 is the same as thatshown in Fig. 3

and is made of metal, the rod 7 which supports it constituting one ofthe leading-in wides, while the other leading-in wire 4? is branched andthe branches connected one to each of the filaments 9", 10 which arethus arranged electrically in parallel.

These lamps can be made at a cost only slightly greater than the usualplain type of lamp, and when employed in the usual paraboloid reflectorfulfill every requirement of a legal, safe and convenient driving lamp.Their range of permissible adjustment is much greater than that of theusual lamp, and all the light emitted is employed usefully. It will beunderstood that many modifications in the details of manufacture can bemade in addition to those herein pointed out which are intended merelyas examples of what may be done in connection with my improvements, andI do not limit myself in any wise except as defined in the claims heretoannexed.

Having thus described my inventiomwhat I claim is:

1. In an automobile headlight, in combination, a paraboloid reflectorarranged with its axis substantially horizontal, a pair of light sourcessupported substantially on the axis of said reflector on opposite sidesof its focal point, and individual reflectors for said sources, one ofsaid individual reflectors facing upwardly and the other facing downwardly, the source which is forward of the focal point being located inthat individual reflector which faces upwardly and the source which isat the rear of said focal point being located in that individualreflector which faces downwardly.

2. In an automobile headlight, in combination, a paraboloid reflectorarranged. with its axis substantially horizontal, a pair of lightsources supported inside and individual oppositely facing reflectors forsaid sources, one

of said individual reflectors facing upwardly and the other facingdownwardly, the margin of each of said last named reflectors extendingsufficiently beyond the corresponding light source to prevent any raysof the same from falling on the horizontal portion of the first namedreflector.

In testimony whereof, I hereunto affix my signature.

EMERSON B. HELM.

